Cryptocurrency Carbon Footprint Calculator — CO₂ per Transaction

Formula

How this is calculated

The environmental cost of a blockchain transaction comes from two factors: the energy needed to process and record it, and the carbon intensity of the electricity grid that powers the miners or validators. Multiplying energy per transaction by the number of transactions gives total electricity consumption in kWh; multiplying by the grid's carbon intensity (kg CO₂ per kWh) gives CO₂ emissions.

Energy per transaction varies enormously by consensus mechanism. Proof-of-work coins like Bitcoin expend energy on competitive hashing: Cambridge Centre for Alternative Finance (CBECI) and Digiconomist estimated Bitcoin at roughly 600–1000 kWh per on-chain transaction in 2024, depending on methodology and assumptions about miner revenue allocation. Proof-of-stake Ethereum (post-Merge, September 2022) reduced per-transaction energy to roughly 0.002 kWh — a >99.9% drop. All figures change as hash rate, transaction volume, efficiency and energy mix evolve, so the defaults are 2024 estimates that you should update from current sources.

Grid carbon intensity defaults to 0.40 kg CO₂/kWh, the approximate IEA global average for 2024. Bitcoin mining increasingly uses renewable or stranded energy in some regions, which can lower real-world emissions well below the grid-average estimate; conversely, coal-heavy grids can exceed 0.8 kg CO₂/kWh. The car-equivalent uses ICCT 2024 average passenger-vehicle emissions (0.170 kg CO₂/km); the tree-absorption figure uses the US EPA estimate of 21.77 kg CO₂ absorbed per tree per year.